There is an ever-increasing need to obtain localized heating at home and in the work place. There is also an ever-increasing need to obtain localized cooling or ventilating air flow in those places. As costs rise and incomes fall in a declining economy, the need to obtain a variety of such functions in a single portable appliance becomes more and more advantageous.
Existing air blowing appliances typically prevail in two main types; axial fans and centrifugal blowers. Axial fans have an electric motor typically oriented such that its rotational axis is aligned with the direction of air movement. An air propeller affixed to the motor's rotor rotates about the axis and causes air to be pushed forwardly from the fan in the direction along the axis. Centrifugal blowers have an electric motor typically oriented such that its rotational axis is perpendicular to the direction of air movement. A blower wheel affixed to the motor's rotor rotates about the axis and causes air to be pulled into the wheel, and then pushed outwardly and forwardly from the appliance.
Blower wheels include a plurality of peripherally disposed vanes, which rotate concentrically about the wheel's axis as the blade rotates. Such vanes are sometimes straight, and extend radially from the wheel's axis as spokes from a wheel. Such straight, radially-disposed vanes cause the wheel to be equally efficient in either rotational direction, hence, optimal in neither. Such wheels are useful in reversible blowers for causing an equal airflow in either direction, although less than optimal in both, according to the rotational direction of the wheel.
In order to optimize airflow from a centrifugal blower wheel, the vanes are typically curved into the direction of the wheel's rotation to increase air-producing efficacy. Curvature opposite to such a “directional” wheel's rotation results in a loss of efficacy, and a less voluminous and more turbulent airflow. So that a wheel that is optimized for say the clockwise (right-handed) rotational direction, would have vanes that curve to the right as they extend from the wheel's axis, and would produce airflow efficiently when the wheel is rotated clockwise. But such a wheel would produce a less voluminous and more turbulent airflow is the wheel's rotational direction was reversed to counter-clockwise. It has therefore been inconceivable to date that a directional blower wheel would be useful in a reversible application.
Certain electrical air heaters also incorporate such a blower wheel along with a heating element. Air is pushed or pulled through the element to be warmed before it exits the appliance. While airflows from cooling appliances are preferably made high to cause a “wind chill” effect when the airflow impacts the user, airflows are preferably made low from air heaters to avoid such an effect, which would contradict their intended warming function.
Variable air flow rates from centrifugal blowers are typically achieved by variation of the motor speed, either by using a speed controller or by including a multitude of taps into the motor coil, either of which adds cost, complexity, and an additional opportunity for failure compared to a single speed blower.
There exists the need for an efficient portable air blowing appliance which selectively provides cooling at a higher airflow, and warming at a lower airflow and such is an object of the present invention.
There exists the need for such an appliance which selectively provides either airflow without the need for a speed controller, and such is an object of the present invention.
There exists the need for such an appliance which selectively provides either airflow without the need for a multiple-speed motor, and such is an object of the present invention.
There exists the need for such an appliance which selectively provides either airflow without the need for multiple motor coils or taps, and such is an object of the present invention.
Other needs and objects will become apparent upon a reading of the following disclosure in combination with the appended drawings.